1. Field of Invention
This invention relates to a knee brace with a posterior strut and generally triangular stiff cuff members which transmit forces around the knee joint, and more particularly to such a knee brace in which the rigid posterior strut is adjustable in several degrees of freedom to accommodate for a wide range of abnormalities in, and sizes of, the protected joint.
2. Background Information
Our copending application Ser. No. 07/662,879 filed on Mar. 1, 1991 now U.S. Pat. No. 5,133,341 and entitled "Knee Brace with Posterior Strut" discloses a unique knee brace having a rigid posterior strut with an arcuate section extending through the popliteal space behind the knee joint and terminal portions positioned on either side of, but spaced from, the joint. A superior elongated support member is pivotally connected to one terminal portion of the strut and extends upward along one side, preferably the medial side, of the thigh, and is secured to the fleshy part of the thigh by cushioned straps. An inferior elongated support member is pivotally connected to the other terminal portion of the strut and extends downward along the opposite side, preferably the lateral side, of the leg and is secured to the fleshy part of the leg by additional cushioned straps.
The posterior strut of this brace performs several functions. First, it is the basic element to which the other components of the brace are attached. Second, it transmits forces applied to the lateral side of the knee around the joint to the medial side and into the fleshy part of the thigh through the hinged support. Similarly, medially applied forces are transmitted around the knee joint by the posterior strut to the lateral side where they are dissipated in the fleshy part of the leg.
A third and very important function of the posterior strut is the repositioning of the hinge points for the support members on the terminal portions of the strut to accommodate for femoral rollback during flexion of the joint. This repositioning is effected by rotation of the arcuate portion of the strut which is clamped between the fleshy portions of the backs of the thigh and the calf. This construction eliminates the need for the very complex compound hinge mechanisms found in many knee braces.
The knee brace of our copending application also preferably includes a pair of stiff, bowed anterior cuffs. These cuffs are generally triangular in shape with one edge secured to one of the elongated supports and the opposite vertex pivotally connected to the opposite terminal portion of the strut. These stiff cuffs, together with the posterior strut, transmit torsion forces around the knee joint without interfering with normal flexion of the joint. As an elongated support need only be attached to one side of the thigh and the other side of the leg, the unique Z configuration of our knee brace makes it easier to fit the brace to the wearer, while providing superior protection. In an alternative, functional (special application) form of the brace, elongated support members hinged to both the terminal portions of the posterior strut extend upward and downward and are attached to the lateral and medial sides of both the thigh and the leg. Pairs of criss-crossing, stiff, anterior cuffs are secured to each of the elongated support members and are pivotally connected to the opposite terminal portion of the posterior strut.
While the knee brace of our copending application provides very good support for an injured, diseased or malformed knee joint, there is a need for a knee brace with a posterior strut which can be readily and easily adjusted to accommodate for individual knee characteristics and provide the surgeon/physiotherapist with a means for adjusting for abnormal knees for either improved brace fit, optimizing brace function/action for individual patients, or compensating for or controlling specific motions or actions. Adjustments may also be required or desirable during the course of treatment to accommodate for reduction in swelling, changes caused by treatment, or growth as in a child. It would also be desirable to have a single, or only a few basic sizes of the brace, which could be readily adapted to the circumstances, as opposed to the custom modeling and fabrication or the stocking of numerous sizes as required by many other braces.